A young friend was talking to me about an idea he had about adding a LED display to the visor on the helmet of one of his cosplay outfits.  He had thought about making a matrix of RGB LEDs and was wondering how he could control them.

A quick search on Ebay found the flexible LED matrix shown in these photos.  It is an 8x32 matrix using WS2811 RGB LEDs.

Since the LED matrix operates of 5 volts,  I constructed a small board based on a Microchip dsPIC33EV256GM102, which is also a 5 volt device.

The matrix is electrically a long line of LEDs that zig-zags down the length of the matrix.  I wrote a piece of software that maps an 8x32 buffer onto this line of LEDs and shifts the data serially to the LEDs.  Other routines were created for plotting RGB values into the buffer.